Bacillary angiomatosis in an immunocompetent child: a case report and review of the literature.

Bacillary angiomatosis is an infectious disease caused by 2 gram-negative bacilli, Bartonella henselae and Bartonella quintana. This disease is characterized by vascular proliferations in the skin and/or visceral organs, and typically manifests in immunocompromised patients. However, we report a case of a 10-year-old immunocompetent female child with a questionable history of being scratched by a cat. Although initially diagnosed as a pyogenic granuloma, a diagnosis of bacillary angiomatosis was made based on histologic examination of the excised lesion demonstrating interstitial bacillary deposition on Warthin-Starry silver stain. The patient was successfully treated with 2 weeks of azithromycin after which all symptoms resolved.

A rare case of a cutaneous squamomelanocytic tumor: revisiting the histogenesis of combined neoplasms.

We describe what we believe to be the seventh report of a combined tumor with histologic features of both malignant melanoma and a squamous cell carcinoma, a squamomelanocytic tumor. An 82-year-old woman presented with a nondescript, skin-colored, firm papule on her nose. Histology showed 2 different neoplastic cell proliferations: atypical squamoid cells and irregularly shaped nests of atypical pigmented epithelioid cells (melanocytes) arranged in small to large nests at the dermal-epidermal junction and within the epidermis. Both components were closely admixed and restricted to the epidermis. Immunohistochemistry showed diffuse cytoplasmic reactivity for pancytokeratin in all areas supporting the histopathologic features of a squamous cell carcinoma. S-100 and melanoma antigen recognized by T cells 1 did not stain these areas and showed strong selective positivity for the atypical melanocytic component. A true malignant proliferation of 2 distinct cell phenotypes due to close paracrine interactions is our favored interpretation because of the intimate admixture, distinct immunohistochemical pattern, and unique histologic features. Perhaps, chronic sun damage (facial location and advanced age) and reduced immunity (history of other malignancies, particularly recent history of a basal cell carcinoma) played a complementary role for the development of the squamomelanocytic tumor.